California Trip

I recommend searching for "Yosemite" in this forum and go back in the archives to get recommendations for campgrounds outside of the park. The small towns of Midpine and Mariposa have some private parks. Also, Indian Flat has a park just outside of Yosemite. Not much to speak of as a park but convenient. Book as soon as you can as they will fill up quickly. You can stay there and drive your toad into the park. Once you find a parking place, ride your bicycles if you have them or take the shuttle to get around the park. Spring is when you see the awesome water falls but early fall is a nice time as well. Yosemite is always busy! If you come in Spring from the Eastern side of the Sierras, Tioga Pass could be closed due to snow as they don't keep it plowed/cleared. In that case, you would need to come into the park from the western routes. You can still get to most of the park and see its beauty. Have fun planning!
In respect to Sequoia National Park, I also like Sequoia RV Ranch in Three Rivers.

I understand the desire to avoid the winter, but some of us really like the Sequoias in the snow -- that's DW in the lower right corner, and no, this is not a trick shot -- they are huge:


Click For Full-Size Image.

We also like Yosemite in the winter -- much quieter than at any other time. It does not get that cold in either park -- rarely below 20 degrees. With proper clothing, it is a lot of fun, and beautiful, too.

I live in So Cal and will let others advise you on your route.

But a bit of advice I can give you is for Sequoia, stay at Sequoia RV Ranch in Three Rivers. Hands down the nicest campground in the Sequoia area.

I'd suggest a full day each in Sequoia and Kings Canyon but at least five days in Yosemite. September in YNP is nice but unlike this year the falls may be dry. So April or May is my suggestion. No guarantees regarding access to YNP via Tioga Pass. Watch road conditions. YNP is wonderful and more you explore the more you'll see to explore. Best way to see the valley floor? Bicycle. Eat dinner at the Ahwahnee Hotel...by candlelight.